System and method of flexibly sorting and unloading finished parts during part manufacturing process

ABSTRACT

The present invention relates to a system and method therefor of sorting and unloading various pieces cut from sheet blanks which have different dimensions in a sheet metal fabricating environment. To achieve this end, prior to the production run, the various program routines whose operations for effecting the cutting of the sheet blanks are retrieved and the data relevant to the to be cut pieces are grouped and analyzed so that pieces of different dimensions cut in accordance with the different program routines are respectively allocated to the corresponding sorting addresses for unloading. Accordingly, different pieces with the same dimension cut from different program routines during the same production run are unloaded to the same location of the unloader area. Optimization of the unloading process and optimal utilization of the available loading space are thereby achieved.

FIELD OF THE INVENTION

The present invention relates to manufacturing processes in a sheetfabrication environment and more particularly to a system and processtherefor to sort and unload finished pieces in a flexible manufacturingsystem.

BACKGROUND OF THE INVENTION

In a numerically controlled sheet fabrication center, to produce partsfrom sheet blanks, part programs or routine files are used. Ordinarily,these part programs are stored in data banks so that an operator canretrieve one or more for each production or batch run. If the partdesired has never been produced before, a new part program, or routinefile, has to be written by a programmer for effecting that particularpart from a sheet blank.

Each part program is considered a file and includes geometrical andtechnological definitions of the to be cut part. Some of thetechnological definitions include tooling data (size and shape of thetool, angle and position of tool changer, etc.), the order of toolingoperation (which tool operates first, second, etc.), and the workingsequence of a tool (what operations the tool performs and in whatsequence—also known as optimized tool path). Among technologicaldefinitions, an important one is the sorting address, which is thelocation where a finished part is placed by the system.

Production requirements in sheet fabrication centers are such thatcertain parts need to be produced within a given delivery time. Toachieve this end, programmers are given a list of parts that arerequired so that they can write a “nest program” for producing thoseparts. Some of the parameters which are utilized in a nest programinclude the sheet blank sizes that are available and the requiredmaterial thickness. The nest program will select from among theavailable sheet blanks the one with the size that is most suitable foroperation. In particular, in a nest program, the required differentparts are laid out in accordance with the dimension of the selectedsheet blank in an optimal fashion to maximize material utilization. Inother words, scraps from the sheet blank are to be minimized.

The nest programs are run in the system sequentially. As parts definedby each of the nest programs are produced, they are sorted and directedto sorting addresses pre-defined for them in the nest program. Nestprograms can be generated automatically from given productionrequirement lists and existing program files or routines. One existingsoftware for defining such nest program is the JETCAM from theFinn-Power company.

The sorting addresses refer to the different locations in the unloadingarea of the part sorting and unloading system to which finished partsare to be placed. When a sorting address becomes full or when theproduct run is completed, the parts have to be removed from the sortingand unloading system in order to make room for the next production run.The operation for the removal in most cases involves manual labor.However, in advanced flexible manufacturing systems, such removal ofparts may be done automatically.

The sorting and unloading of finished parts to different sortingaddresses ordinarily proceeds uneventfully. However, in practice, giventhe limited quantity of available sorting addresses and the very largeor unlimited quantity of different parts, problems do occur. Forexample, a produced part may have a sufficiently large dimension tocover more than one conventional sorting address to thereby limit thenumber of available sorting addresses in the system. Alternatively, ifthe production run requires that a large quantity of differentlydimensioned parts be produced, then there may not be sufficient sortingaddresses.

Yet another problem that occurs is when parts from different nestprograms in the same production run have been designated by therespective nest programs to have the same sorting address or overlappingaddresses. In this instance, insofar as the controller has no way ofarbitrating which part from which nest program should take precedenceover a particular sorting address, oftentimes the production run isstopped to allow the programmer/operator to effect modifications to thenest programs to rearrange the sorting addresses so that all parts maybe sorted properly. Needless to say, this stopping of the system duringa production run leads to inefficiency, lost production time, increasedproduction cost and delivery times, and additional reset work torearrange the sorting addresses.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

To overcome the above problems, the present invention systemincorporates a “denester” approach in which, prior to a production run,all of the nest programs to be run during the production are reviewedand all data relevant to the to be cut pieces are retrieved. Therelevant data may include, for example, the sizes and dimensions of allof the parts to be cut during the production run with each of the nestprograms. The dimensions from the different parts are then resorted andassigned to respective sorting addresses. Parts that have the samedimensions are assigned the same sorting address so that those sameparts are directed to a particular location at the unloading area of thesorting and unloading system.

Since all the parts to be cut during the production run are analyzed—atleast with respect to the respective dimensions and the number of thoseparts to be cut—prior to the production run, as parts are cut during theproduction run, those parts are directed to the sorting and unloadingsystem in a predetermined fashion such that each part is directed to acorresponding sorting address. Since like parts are directed to the samesorting address, no conflict would arise even when sheet blanks are cutinto different dimensioned pieces in accordance with different nestprograms. Thus, with all part sizes, quantity and quality informationpredetermined, layouts for the sorted parts, in terms of the unloadingarea to which the sorted pieces are to be placed, is optimized so thatall of the available part sorting addresses in the system are utilizedto maximum capacity. No sorting address is therefore “overloaded” or“under utilized”. Moreover, the production run will not be stopped onaccount of any potential “address flow alarm” or “sorting addressconflict” in the middle of the production process. The setup timetherefore decreases while production run efficiency increases.Furthermore, no intervention by the programmer/operator is required.

In the event that new nest programs are added during the production run,insofar as sorting addresses for the different dimensioned cut pieceshave already been determined, the different pieces to be cut from eachof the newly added nest programs can readily be routed to theappropriately predetermined sorting address. And a new sorting addressis automatically calculated by the processor of the system for any ofthe to be cut pieces from any of the newly added nest programs whichdoes not have a corresponding predetermined sorting address.

The calculation of any such new sorting address takes into considerationthe unused space, if any, that is available at the being operated onunloading area. If no unused space is available at the being operated onunloading area, a new sorting address is created at a new unloadingarea. The being operated on unloading area is replaced by the newunloading area when the system begins to cut pieces from a work blank inaccordance with the newly added nested program.

With the present invention system and method, a number of sorting andunloading systems can be utilized. Thus, different sorting addresses maybe assigned to different systems. Some such exemplar sorting andunloading systems include a conveyor mechanism, a sorting device, arobot unloader mechanism, and a stacker mechanism.

An objective of the present invention is therefore to provide a systemand method for ensuring a smooth production run in a sheet fabricationsystem.

It is yet another objective of the present invention to provide a systemand method for ensuring optimal utilization of sorting addresses andtherefore efficient unloading of cut pieces of different sizes and/ordimensions.

It is still another objective of the present invention to provide asystem and method in which cut pieces of the same dimension are stackedin an unloading area of a pallet, storage bin, or cassette such that theavailable space of an unloading area is efficiently utilized.

BRIEF DESCRIPTION OF THE FIGURES

The above mentioned objectives and advantages of the present inventionwill become more apparent and the invention itself will be bestunderstood by reference to the following description of an embodiment ofthe invention taken in conjunction with the following drawings, wherein:

FIG. 1 is a perspective view of a flexible manufacturing systemutilizing the instant invention;

FIG. 2 is a flow chart giving a generalized overall view of theoperation of the instant invention system;

FIG. 3 is an exemplar batch processing sheet illustrating an exemplarproduction run of the system utilizing three different nest programs;

FIG. 4 is an illustration of the parameters for the first nest program;

FIG. 5 is an illustration of the layout of pieces to be cut from a sheetblank in accordance with the nest program of FIG. 4;

FIG. 6 is the setup illustration of the parameters of to be cut sheetsfrom a second nest program;

FIG. 7 illustrates a layout of the sheets to be cut from a sheet blankfrom the nest program of FIG. 6;

FIG. 8 is an illustration of the last exemplar nest program for theexemplar production run of FIG. 3;

FIG. 9 is an illustration of the layout of the pieces to be cut inaccordance with the nest program of FIG. 8;

FIG. 10A is a plan view of a stacker sorting mechanism to be used withthe instant invention system;

FIG. 10B is a side view of the FIG. 10A stacker sorting mechanism;

FIG. 11 is an illustration that shows the different sorting addresses ofthe available space of an unloading area to which finished pieces are tobe moved;

FIG. 12 is an illustration of another exemplar layout of the sortingaddresses of the available space of an unloading area; and

FIG. 13, comprising FIGS. 13A, 13B, 13C and 13D, is a flow chartillustrating the operation of the instant invention method.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

With reference to FIG. 1, the flexible manufacturing sheet fabricatingenvironment of the present invention system and method is shown. Inparticular, such flexible manufacturing system includes, among othercomponents, an automatic storage system 2 in which sheet blanks orworksheets of various sizes are stored. These worksheets can each beloaded from the different bins of the storage system onto its conveyor 4to be transported to the conveyor of a loading system 6. There, theworksheet is picked up by a loading mechanism 8 and transported to amachine center 10, which may comprise a turret punch press wheredifferent tools are used to effect different desired holes onto theworksheet. Adjacent to the turret punch press but also residing at themachine center 10 is a right angle shear system 12 for cutting piecesfrom the worksheet. The respective operations of the storage system 2,loading system 6, turret punch press and right angle shears arecontrolled by a numerical controller 14. Further controlled bycontroller 14 are an unloading device mainly comprising an unloading arm16, an unloading/sorting device 18, an unloading/sorting conveyor system20 and a stacker/unloading system 22.

The fabrication of worksheets from storage system 2 by either the turretpunch press or the cutting shears, or other part fabricating devicessuch as laser or plasma cutters or bending machines, at machining center10 is performed in accordance with program routines or files stored incontroller 14. Some of these programs are so-called “nest” programs inwhich the pieces to be cut from a sheet blank are predefined accordingto their respective dimensions so that an optimal number of pieces maybe cut from the sheet blank. Examples of layouts of pieces to be cutfrom worksheets are shown in FIGS. 5, 7 and 9, each to be discussed indetail further.

After being cut from a worksheet, the finished pieces are eitherunloaded by the unloading arm 16, or conveyed to sorting unit 18,conveyor system 20, or stacker/unloading system 22, in accordance withthe particular operations of the different program routines. Putting itdifferently, a finished piece may either be conveyed to sorting unit 18,the multi-sectioned conveyor 20 and/or stacker/unloading system 22. Asshown, sorting device 18 has a storage bin 24. For the multi-sectionedconveyor 20 (one section of which is shown to be pivoted upwards), anumber of storage bins 26 are shown to be placed under the respectivesections of the conveyor. As for stacker/unloading system 22, there isshown a cassette 28 onto which a plurality of pallets 30 are placed. Aplurality of stacks of finished pieces in turn are placed on each of thepallets. As shown, cassette 28 is fitted with rollers resting on trackswhich allow it to be positioned underneath the stacking mechanism ofstacker/unloader system 22. A more detailed discussion of thestacker/unloading system 22 will be given later.

FIG. 2 provides a general description of the operation of the flexiblemanufacturing system of FIG. 1. To begin, production requirements areinput to the controller by way of keyboards, tapes, an input panelattached to the controller, or other conventional input means per step32. Such production requirements include, among other parameters, thenumber of pieces to be cut from a worksheet, the thickness of theworksheet, the sizes and/or dimensions of the respective pieces to becut, how many sheet blanks are to be processed, the respective sizes ofthe sheet blanks to be used, the types of materials to be used, thetypes of tools to be used, and the type of processing to be performed bythe different tools, etc. These production requirements are used forprogramming and nesting parts to the sheet blanks per step 34.

More particularly with respect to step 34, nest programs, i.e., programroutines, for performing work on worksheets are formulated, written andinput in this step. The respective summaries of three different nestprograms are shown in FIGS. 4, 6 and 8. In essence, what a nest programdoes is to guide the system in its fabrication of the differentworksheets during the production run, i.e. the different operations thattake place during the running of the program routine. Since ordinarily anumber of nest programs are performed for each production run, differenttypes of operations would occur at different times of the productionrun. The thus produced parts are sorted to different unloading receiverssuch as pallets in step 36. Thereafter, the finished parts are removedfrom the pallets per step 38.

For demonstration purposes, an exemplar batch processing summary isprovided in FIG. 3. As shown, there are three nest programs (001, 002and 003) to be executed during the production run. These programroutines are designated by the line entitled “DNC Number in the Batch”.As designated by the line entitled “Blank Sheet Size”, for nest program1, each worksheet is arbitrarily chosen to have a dimension of 96×48inches. For nest program 2, the size of worksheets to be worked on isarbitrarily chosen to be 120×60 inches; while the size of worksheets tobe operated on by nest program 3 is arbitrarily chosen to be 96×48inches. It should however be appreciated that the size of a worksheet isnot important for the operation of the nest programs.

For the exemplar nest programs shown in the line entitled “Blank Sheetsto Process”, one worksheet is to be operated on by each of those nestprograms. As formulated, program 1 utilizes 91 percent of its worksheetwhereas programs 2 and 3 each utilize 90 percent of their respectiveworksheets, per line entitled “Material Usage”. Further with respect tothe portion designated 40, seven different parts, or finished pieces,are to be produced from the three different nest programs during theexemplar production run. For instance, during the operation of nestprogram 1, 8 part 3 pieces, 3 part 5 and 15 part 6 pieces are produced.For nest program 2, in the meantime, 10 part 3 pieces, 9 part 4 piecesand 4 part 5 pieces are produced. Finally, in nest program 3, 7 part 1pieces, 5 part 2 pieces, 2 part 3 pieces, 10 part 4 pieces, 13 part 5pieces, 5 part 6 pieces and 1 part 7 piece are produced.

To provide further detailed description of the individual nest programs,refer to program 1 as illustrated in FIG. 4. Under the heading“COMPONENT(S):” the respective dimensions of part 3, part 5 and part 6are shown. Specifically, part 3 pieces are shown to have a size of 44×11inches; part 5 pieces 15×3.875 inches and part 6 pieces 3×3 inches.Under the heading “RUN TIME ESTIMATION-OPTIMIZED”, the number of “SingleHits” to be effected by the chosen tool is to be 827. There is to be nonibbling since the “Nibble Hits” is zero. The total distance to betraveled by the to be worked on sheet blank is 1688.7993 inches. Toperform nest program 1, the total number of “Tool Changes” is 5 whilethe “Total Time” in which the sheet will be operated on is 6 minutes and31 seconds. The types of tool to be used are listed in the sectionentitled “TOOL ASSIGNMENT LIST”.

With reference to FIG. 5, the layout over a representative worksheet tobe worked on is shown. There the worksheet is designated 42, which is tobe held by three clamps 44. The pieces to be worked on and cut fromworksheet 42 can be seen to comprise 8 pieces of part 3, 3 pieces ofpart 5 and 15 pieces of part 6. Thus, a total of 26 pieces are to be cutfrom worksheet 42. Each of the to be cut pieces in turn is to be workedon by the different tools, as noted in FIG. 4, before the respectivefinished pieces are cut from the sheet blank. Prior to the instantinvention, the way in which the different pieces are laid out, forexample as shown in FIG. 5, would be sorted and unloaded the same wayonto a pallet. However, as was mentioned previously, given that a numberof nest programs are performed during a given production or batch run,conflicts in regard to the respective sorting addresses to which the cutpieces are to be moved oftentimes arise. When there is a conflict, thesystem would shut down or cease further operation until anoperator/programmer can sort out or prioritized the different cut piecesfor the different sorting addresses. Such conflict will be apparent inview of nest programs 2 and 3, to be discussed with reference to FIGS. 6to 9 below.

As shown in FIG. 6, nest program 2 is defined to perform certainoperations for fabricating from a sheet blank 3 types of cut pieces,namely part 3, part 4 and part 5. The total number of pieces to be cutfrom the sheet blank is 23, with 10 pieces of part 3, 9 pieces of part 4and 5 pieces of part 5. The layout for cutting the pieces from aworksheet 46 is shown in FIG. 7. It should be noted that worksheet 42 ofFIG. 5 has an arbitrary dimension of 96×48 inches whereas sheet 46 ofFIG. 7 has an arbitrary dimension of 120×60 inches. Thus, 10 pieces ofpart 3 can be cut from the more spacious worksheet 42, as compared toonly 8 pieces of the same part 3 being able to be cut from the nestprogram of FIG. 4.

Continuing with the last of the nest programs for the exemplarproduction run, it can be seen from FIG. 8 that the worksheet,designated 48 in FIG. 9, to be used for this nest program has adimension of 96×48 inches. From worksheet 48, 43 separate pieces are tobe cut. These separate pieces are specified under the heading“COMPONENT(S):” and are as follows: 2 pieces of part 3, 10 pieces ofpart 4, 13 pieces of part 5, 7 pieces of part 1, 5 pieces of part 2, 1piece of part 7 and 5 pieces of part 6. The respective layouts of thesepieces are shown in FIG. 9. Note the minimization of scraps forworksheet 48 as the different pieces are laid out. For example, 4 of thepart 2 pieces are clustered in one section of worksheet 48 while theremaining part 2 piece is by itself.

From the layouts of FIGS. 5, 7 and 9, it can be seen that not only doeseach of the nest programs cut finished pieces from sheet blanks that maybe of different dimensions, the respective layouts of the differentparts to be cut from each sheet blank are different, i.e. the same piececut from each sheet blank may be cut from a different location dependingon the operations of the particular nest program. Witness the differentnumbers and locations of part 3 pieces to be cut from the differentlayouts of FIGS. 5, 7 and 9.

The fact that the same pieces may be cut from different locations ofdifferent sheet blanks would not pose any problems if the cut piecesfrom each sheet blank were to be placed the same way on separatereceiving pallets, storage bins or cassettes. However, this entails aninefficient operation in which an unacceptable large number of receiverdevices have to be put into operation. This is unrealistic since only agiven number of pallets or storage bins, not to mention cassettes, maybe effectively put into use at any one time.

The present invention solves this problem by assigning respectivespecific sorting addresses for to be cut pieces of different dimensionsirrespective of whichever nest program, and whatever type of sheetblank, the pieces are to be cut from. To achieve this end, prior to theproduction run, the available area onto which finished pieces are to beplaced is sub-divided into zones or locations each designated with aparticular sorting address. In particular, prior to a production run,the relevant data from each of the nest programs that are to be operatedon during the production run are collected and analyzed by the systemprocessor. The relevant data may include for example the sizes anddimensions of all of the pieces to be cut from the different worksheetfrom each of the nest programs. The cut parts that are to have the samedimension, irrespective of whichever nest programs and/or worksheetsthey are to be produced from, are assigned the same sorting address soas to be unloaded onto the same location of an unloading area. Takinginto consideration the thickness of the different cut pieces, more thanone sorting address may be assigned to cut pieces having the samedimension. This being necessitated by the fact that cut pieces may bestacked only to a predetermined height. In other words, once a stack ofcut pieces of a given dimension has reached a predetermined height, cutpieces of the same dimension are necessarily routed to a second sortingaddress at the same unloading area, or another unloading area, i.e.another pallet, storage bin or cassette. This use of alternate sortingaddresses for the same dimensioned cut pieces can continue ad infinitum,as long as there are available space in the unloading area, or if thereare additional unloading areas. Such is the “denester” approach of theinstant invention.

For the present invention, during the production run, new nest programsmay be added. As each of the new nest programs is added, its relevantdata are extracted and analyzed, so as to be compared with thepreviously extracted and analyzed data of the nest programs input priorto the production run. Cut pieces of a dimension that had previouslybeen assigned a sorting address at an unloading area are of course alsorouted to that area. Each of the cut pieces that has a new dimension isassigned a new sorting address, which may designate an unused space inthe unloading area that is in operation, or a new unloading area. Howdifferent unloading areas may be utilized will be discussed furtherbelow.

Insofar as the instant invention system utilizes a number of differentsorting and unloading systems, different setups of sorting addresses areused for each of the mechanisms. For example, return to FIG. 1. There,it can be seen that there are a conveyor sorting mechanism 20, a sortingunit 18 and a stacking/unloading system 22.

To enhance the understanding of how the different pieces are to be movedto different sorting addresses of stacking/unloading system 22 so thatpieces of different dimensions may be placed onto the available storagearea of the system, such as that on cassette 28, a more detaileddescription of the operation of the present invention unloading/stackingsystem is given hereinbelow with reference to FIGS. 10A and 10B.

As shown in the plan view of FIG. 10A and the cross sectional view ofFIG. 10B, the stacker mechanism of the instant invention system isenclosed in a housing 50 to enhance safety. To allow easy viewing fromoutside of housing 50, a number of windows 52 are provided. The stackermechanism is mounted on cross frames 54 supported by four columns 56. Aplurality of retractable rollers 58 provide the base for the stackermechanism onto which finished pieces are conveyed and moved. For thesake of clarity, only a limited number of rollers 58 are shown in FIG.10A, albeit it should be noted that each of the lines 60, in actuality,represents one of the rollers. Thus, given the plan view of FIG. 10A, acut piece 62 is provided to the stacker mechanism (possibly via conveyorsystem 20 of FIG. 1) as indicated per directional arrow 64.

Overhangingly mounted to the frame of the stacker mechanism is astationary beam 66 perpendicularly on which a number of cross beams 68are mounted. As shown, mounted to beam 66 are a number of guides 70 eachcomprising a number of extending fingers 72 each interspersed betweentwo adjacent rollers 58. Guides 70 each are movable and are drivenvertically by a motive means such as for example a hydraulic cylinder74. In the up position, fingers 72 are positioned away from plane of 76of FIG. 10B, which represents the surface of a storage area, for examplethat of the cassette 30 shown at its loading position 30L. When down,the tips of fingers 72 form a partition on the surface of the storagearea, as shown in FIG. 10B.

Movably mounted across cross beam 68 is a support beam 76 onto which anumber of guides 78, movable vertically, are mounted. Similar to guides70, guides 78 each have attached thereto a plurality of extendingfingers 80 bent as shown in FIG. 10B. Similar to fingers 72, fingers 80may be moved vertically by means of driving mechanisms such as hydrauliccylinders 82 shown in FIGS. 10A and 10B. Beam 78 is movable along the Ydirection, and is driven by a servomotor 84 and its corresponding ballbearing 86. Thus, as beam 76 is moved along the Y axis, fingers 82likewise are moved along the same axis. It should be noted that fingers82, like fingers 72, are mounted to be interspersed between adjacentrollers 58 when they are in the down position to form a boundary onsurface 76 of the storage area.

For the embodiment stacker mechanism shown in FIGS. 10A and 10B,pivotally mounted to each of cross beams 68 is a stop 88 which can bepivoted to the down position, shown in FIG. 10B, for stopping themovement of a cut piece conveyed along rollers 58. When pivoted to itsup position (not shown), a cut piece can slide thereunder as it isconveyed by rollers 58. For the embodiment shown in FIG. 10A, there arefour stops 88 a, 88 b, 88 c and 88 d for separating the stackermechanism into four areas, or cells, each being roughly divided by apair of stoppers 88 and cross beams 68. It should be appreciated thatmore (or less) than four stops may be utilized so that the stackermechanism may be subdivided into a greater (or smaller) number of areas.

Although not shown clearly, each of rollers 58 (60) is driven, forexample by motor 90 shown in FIG. 10B. Each successive adjacent pair ofrollers 58 are bounded by a belt or chain so that as motor 90 rotates,each of the rollers would likewise rotate. The rotation of rollers 58enhances the conveyance of a cut piece thereon along direction 64. Asmentioned before, rollers 58 are retractable. This retractability iseffected, for two adjacent cells of rollers, by an air cylinder 92mounted on a pair of support beams 94. Provided at each end of aircylinder 92 is a shock absorber 96 to dampen and smooth the movementalong the Y direction of a support 98 to which the rollers are rotatablymounted.

Inasmuch as the rollers of selected cells may be retracted, a cut piecewhich is at rest on those rollers (being kept in place by theappropriate stopper 88), may be dropped from the plane where theconveying rollers are onto a particular location on surface 76 of thestorage area. To elaborate, suppose a cut piece 62 has been conveyedalong direction 64 onto the rollers of the stacker mechanism. Furthersuppose that stoppers 88 a, 88 b and 88 c have been pivoted to the upposition. Given that, cut piece 62 would be conveyed to the cell definedby stopper 88 d. And when air cylinder 92 b is operated to retract therollers 58, cut piece 62 is dropped onto an area below the cell definedby stopper 88 d.

For the instant invention, each of those cells shown in FIG. 10A isgiven a sorting address. For example, cell 88 d may be given a sortingaddress 1, 88 c a sorting address 2, 88 b a sorting address 3, and 88 aa sorting address 4. Of course, if there are more (or less) than fourstops, there would correspondingly be more (or less) than four cells.Instead of separate stoppers, one single movable stopper that can varythe size of the cells along the X direction may also be used.

Alternatively, the sorting addresses may be assigned to the differentlocations on the surface area of the storage device onto where the cutpieces are to be deposited. For example, instead of cell 88 d beingassigned a sorting address, it is the location of the storage area ofthe cassette (or pallet placed thereon) where the cut pieces from cell88 d are to be deposited that is assigned sorting address 1. Likewise,the location onto where cut pieces from cell 88 c are to be deposited isdesignated sorting address 2; that from cell 88 b sorting address 3; andthat from cell 88 a sorting address 4.

A sensor is provided in front of each of the stoppers 88. This sensor,in the form of a movable plate, is used to detect the oncoming of a cutpiece to the particular stopper. The sensor, not shown, provides asignal to the controller to begin the retraction of rollers 58, as itencounters the cut piece. By receiving a lead signal before the cutpiece hits and is stopped by the appropriate stopper 88, the system isable to begin the retraction of the appropriate set of rollers for moreefficient operation. In other words, once the cut piece is detected bythe sensor, a signal is sent to the controller to begin retraction ofthe rollers. Thus, by the time the cut piece is stopped by the stopperfrom further movement (i.e. lined up correctly), the rollers areretracted so that the cut piece is vertically placed or deposited ontothe appropriate location of the storage area, thereby saving productiontime.

As discussed above, insofar as beam 76 is movable along the Y direction,the left extension fingers 80 and the right extension fingers 72together can define a plurality of zones for each of the cells along theY axis. The dimension to be assigned to each of those zones is dependenton the respective sizes of the cut pieces to be conveyed thereto. Forexample, as shown in FIG. 10B, a stack of cut pieces, designated 100, isshown to be confined by fingers 80 and fingers 72. Simply put, each cutpiece of stack 100 has been conveyed to the same cell (or sortingaddress) and deposited onto the same location (or sorting address) ofthe cassette. The bent portion of each finger 80 provides a degree offreedom for the being deposited cut piece to settle into the definedlocation of the storage area. As should easily be recognized, thelocation of the area defined by stack 100 is different from the areadefined by stack 102, whose cut pieces have a smaller dimension, andalso from the area defined by stack 104, whose cut pieces have adimension intermediate of those of the cut pieces of stacks 100 and 102.

To optimally utilize the storage area, as for example the surface ofcassette 30 shown in FIGS. 10A and 10B, the cassette is movable alongthe Y axis, driven for example by a motor 106. Thus, depending on thesize of the cut sheet to be deposited onto the storage area, and furtherdepending on the predefined sorting address to which the cut piece is tobe moved, cassette 30 is moved along the Y axis, as the cut piece isbeing moved along the X axis to its predetermined cell at the stackermechanism, so that a given location of the storage area is positionedbelow the appropriate rollers such that, upon retraction of the rollers,the particular cut piece is deposited onto the given location. Cutpieces having the same dimension are directed to the same cell on thestacker mechanism and the same location of the cassette is moved belowthe appropriate rollers. Accordingly, a stack of cut pieces having thesame dimension is formed as more and more of the same dimensioned cutpieces are deposited onto the same location of the storage area.

The operation of the stacker mechanism and the movement of the cassetteare controlled by controller 14. Instead of being deposited directlyonto the surface of the cassette, a number of pallets, for example thosedesignated 28 in FIG. 1, may be placed on top of the cassette to provideeasier removal of the finished pieces from the cassette. Thus, as mostclearly shown in FIG. 10B, the cassette is movable to its unloadingposition, represented by an outline of the cassette in dotted format,and the loading position, designated by 30L.

Although one cassette is shown in FIGS. 1 and 10 for the sake ofclarity, in practice, a number of cassettes, each positionable under thestacker mechanism, may be used. By systematically positioning differentcassettes, and in particular respective specific locations of each ofthe cassettes, below the appropriate cell of the stacker mechanism, thesystem ensures the smooth operation of the production run. To elaborate,suppose the unloading area of a first cassette has been optimallydivided into seven sub-areas for receiving cut pieces having sevenpredefined dimensions. Now assume that one of the nest programs requiresthe fabrication of cut pieces having yet a different dimension. Giventhe fact that the unloading area of the first cassette has already beendivided into sub-areas none of which is meant to accept the newdimensioned cut pieces, the system would then allocate a new sortingaddress at a given location of a second cassette. Thus, when the timecomes during the production run that cut pieces of the new dimension areto be conveyed to the stacker mechanism, the first cassette (assumingthat it has been positioned underneath the stacker mechanism all along)is automatically removed and replaced by the second cassette, with theappropriate location of the second cassette being placed under theappropriate cell of the stacker mechanism for receiving the newdimensioned cut pieces. The multiple number of cassettes may be sortedin an automatic storage system such as system 2 shown in FIG. 1.

FIGS. 11 and 12 illustrate exemplar layouts of sorting addresses for thestorage areas of a receiver means at the unloading portion of thepresent invention system. In particular, these layouts refer to thestorage area of a cassette to be used to receive deposits of stacks ofcut pieces from the stacker/unloading system 22. It should beappreciated that in place of a cassette, other types of receivers suchas storage bins or pallets may be used. The storage area of eachreceiver is divided into a number of sections with different sortingaddresses. It should further be appreciated that each storage binreceiver can be assigned only one sorting address insofar as the way inwhich cut pieces are deposited into a storage bin is quite differentfrom the way in which cut pieces are deposited on a cassette. This isdue to the fact that most likely storage bins are placed underneathunloading systems such as the conveyor system 20 or the sorting unit 18shown in FIG. 1. Note that a number of storage bins 26 are placedunderneath a corresponding number of conveyor sections each of which hasan end that is pivotable upwards. Note also that one of the conveyorsections has been raised. Thus, the cut pieces which are put ontoconveyor system 20 would be conveyed by the conveyor section to the leftof the upraised conveyor section so that they would shoot into thestorage bin positioned under the upraised conveyor section which hasbeen specifically referenced as 26. Cut pieces of different dimensionsare of course conveyed by different conveyor sections to differentstorage bins, by raising the appropriate conveyor section.

Focus on FIG. 11. There, it can be seen that the storage area of theparticular cassette has a length of 3,020 inches along the X axis and1,500 inches along the Y axis. For the exemplar embodiment shown in FIG.11, the area is divided into 20 different zones, or locations, eachdesignated with a particular sorting address. Given that the stackermechanism shown in FIG. 10A is illustrated as being divided into 4different cells, the storage area of the cassette likewise is dividedinto four sections along the X axis. Thus, sorting addresses 204, 208,212, 216 and 220 correspond to the cell defined by stopper 88 d; 203,207, 211, 215 and 219 defined by the cell of stopper 88C; addresses 202,206, 210, 214 and 218 by the cell of stopper 88 b; and addresses 201,205, 209, 213 and 217 by the cell of stopper 88 a. In order to positionthe respective sorting addresses to be below the appropriate cell, thecassette is movable along the Y axis so that, for example, each ofaddresses 204, 208, 212, 216 and 220 may be placed below cell 88 d.Finished pieces conveyed to cell 88 d can therefore be deposited ontothe appropriate sorting address location.

As should further be appreciated, albeit the storage area has beendefined by 20 sorting addresses, a different number of sorting addressesand therefore areas for storing the finished pieces may also beeffected. This is necessary insofar as pieces of different dimensionsmay be cut and conveyed to the stacker mechanism. For example, withreference to FIGS. 5, 7 and 9, it should be appreciated that pieces suchas part 3 presumably require a space larger than that defined by eventhe biggest of the sorting addresses. In other words, for part 3 pieces,a combination of sorting addresses of FIG. 12 such as 212, 211, 215 and216 is required. The four spaces defined by those addresses areaccordingly redefined as a single area to which a single sorting addresssuch as 212 is designated. See for example FIG. 12 in which the storagearea has been redefined into only 5 sorting addresses of 204, 208, 212,216, 220. For the FIG. 12 layout, it should be appreciated that thosedefined sorting addresses each now cover 3 of the cells (88 d, 88 c and88 b) of the stacker mechanism. For both layouts of FIGS. 11 and 12, itshould also be appreciated that the area along the Y axis defined byeach of the sorting addresses is configured by the movement of extensionfingers 78 relative to the extension fingers 72.

The present invention system takes all of the nest programs, and morespecifically the parameters of the to be cut pieces of the differentprograms, into consideration before the production run and assignssorting addresses for the different locations of the storage area(s).Thus, once production run begins, as the pieces are cut and conveyed tothe appropriate sorting mechanism to be unloaded, each of those pieceswill be conveyed to the appropriate cell of the sorter mechanism (forexample the stacker mechanism) and unloaded onto the appropriatelocation designated by the corresponding sorting address on the storagesurface of the receiver means, be it pallets, cassettes, storage bins,etc. Furthermore, the respective sizes of the different locationsdesignated by the different sorting addresses are predetermined so thatcut pieces of the same dimension are always deposited onto theappropriate location. Accordingly, no conflict exists as the productionrun proceeds, as each of the cut pieces, irrespective of whichever nestprogram orders it to be cut and worksheet from which it has been cut,would end up being deposited onto the appropriate location of thepredetermined receiver means.

As stated before, the sorting mechanism of conveyor system 20 shown inFIG. 1 comprises a multiple number of tiltable conveyor sections. Forthe present invention system, each of the storage bins positioned undera conveyor section is assigned a sorting address.

In addition to the sorting/unloading systems shown in FIG. 1, othersorting/unloading systems may also be used. One such system that comesto mind is a robot arm mechanism which is described in co-pendingapplication Ser. No. 717,897, now U.S. Pat. No. 5,317,516 the disclosureof which is incorporated herein by reference. In brief, such robotsystem operates similarly to the stacking/unloading system 22. Inessence, each of the finished pieces is picked-up by the robot arm andunloaded onto a given storage area in accordance with the particularsorting address of the storage area designated for that type of cutpieces.

The operation of the present invention system denester program isdiscussed herein with reference to the flow chart of FIG. 13. To begin,all production requirements and information for the production run aregathered per step 132. The production requirements may refer to the typeof tools to be used, how many tools are to be used, the type of hits,the time the production is to run, etc. A lot of these productionrequirements are listed in the nest program summaries noted on FIGS. 4,6 and 8.

Having gathered the production requirements and the data relating to theproduction run, nest programs are provided to the controller per step134. The operations of the different nest programs have been discussed,supra, with reference to FIGS. 4, 6 and 8. Moreover, the sequence ofoperations of the different nest programs are decided and the summaryfor performing the nest programs is given with respect to the instantexemplar embodiment in FIG. 3. Thereafter, the number of nest programsto be executed in the production run is determined in step 136. For theinstant exemplar embodiment, as discussed previously, there are 3 nestprograms to be executed.

In step 138, data or parameters relating to the to be cut pieces foreach of the nest programs are retrieved. Some of these data include thesizes or dimensions of the pieces to be cut, the respective thicknessesof the worksheets from which the pieces are to be cut and the number ofpieces to be cut. Next, from the retrieved relevant data of all of thenest programs, the optimal sorting addresses on the receiver area (orthe stacker mechanism) onto which the finished pieces are to be placedfrom all of the nest programs are evaluated in step 140. The purpose ofthis step, in brief, is to “denest” all of the relevant data for each ofthe nest programs and re-organize that data into a single file orprogram routine for which all of the pieces to be cut from the differentnest programs are to be allocated to their respective correspondingsorting addresses.

By performing this step prior to the production run, any conflict thatmay arise from pieces cut from different nest programs that otherwisewould have “hung-up” the system are eliminated, as the different sortingaddresses are allocated to cut pieces of different dimensions. Thus,instead of allocating, for example, sorting address 204 (FIG. 11) topart 1 (per layout of FIG. 9) or part 4, (per layout of FIG. 7), or evenpart 6 (per layout of FIG. 5), with the complete evaluation of thedifferent cut pieces from the different programs, sorting address 204may now be allocated instead to, for instance, part 3 pieces. It ismoreover during this step 140 that the optimal utilization of space forthe storage area is to be determined so that only a minimal amount ofunused space, if any, remains on the storage area of the receiver means.

In step 142, the type of sorting/unloading mechanism to be used for thedifferent pieces to be cut during the production run is determined. Forexample, it may be decided that part 4 and part 6 pieces are to bedirected to corresponding sorting addresses of conveyor system 20 whilethe remaining pieces are to be conveyed to stacker/unloading system 22.For the parts to be diverted to conveyor system 20, each of those partsis assigned a sorting address corresponding to one of the tiltablesections, so that those parts will be deposited into the appropriatestorage bins 26.

A decision is made on whether the cut pieces are to be directed to thestacker/unloading system 22 in step 144. If it is, then furtherevaluation is taken with respect to the thicknesses of the worksheetsfrom which the finished pieces are to be cut, per step 146. The reasonfor this determination is to ascertain the height of each of the stacksof pieces to be deposited onto the cassette 28 (or pallet) positionedbelow the stacker mechanism. To elaborate, suppose the worksheets fromwhich pieces are to be cut each have a thickness of {fraction (1/32)}inch. Further suppose that for safety reasons, a height of 36 inchesseparates the bottom of the stacker mechanism from the surface of thestorage area of the cassette. Naturally, the number of sheets that maybe placed on a given location would be at most 1152 (32×36). Anythingover that would either be hazardous or would cause some problem. Thus,by taking into consideration the thickness of the cut pieces, theprocessor is able to determine the maximum number of pieces that maysafely be provided onto a given location with a particular sortingaddress. Given those facts, a decision can be made to move any cutpieces having the same dimension beyond a given number of pieces (1152pieces for the instant example) to an alternate location via a secondsorting address, to be discussed later.

The pieces to be cut are sorted in accordance to their respectivedimensions per step 148. The system then correlates the thus dimensionedto be cut pieces with previously evaluated corresponding sortingaddresses at the particular sorting mechanism at step 152. Thus, thesystem determines how many cut pieces of a given dimension are to bemoved to a corresponding predetermined sorting address to form a stackof cut pieces of a certain height. (To achieve this during theproduction run, in the case of a stacker mechanism, as was discussedpreviously with reference to FIGS. 10A and 10B, the respective cutpieces are moved individually to the different cells of the stackermechanism. At the same time, the cassette 28 is moved along the Ydirection so as to position the appropriate area thereof underneath thecorresponding cell, so that the appropriate sorting address, withreference to the cassette, is positioned below the appropriate rollersof the given cell. Once the approach of the cut piece is sensed, theappropriate set of rollers begin to be retracted so that once the cutpiece makes contact with the stopper and is held thereby, the rollersare fully retracted to deposit the cut piece onto the predeterminedsorting address location to begin a new stack or to add to the stack ofcut pieces of that given dimension already on the cassette.)

In the meantime, a determination is made on the maximum number of cutpieces for a particular sorting address per step 150. If it isdetermined that greater than the maximum number of cut pieces of thesame dimension are to be fabricated from the different nest programsduring the production run, pieces of the same dimension which exceed themaximum number are programmed to be routed to an alternate sortingaddress on the storage area of the receiver means per step 152. Thelocation for the alternate address naturally is determined to havesufficient area for receiving cut pieces of the same given dimension. Itshould be appreciated that since the “denesting” of the nest programs,there is a ready knowledge of the number of cut pieces of a givendimension to be produced during a production run so that the necessarynumber of alternate sorting addresses may be predefined.

Do note, however, that there is always the possibility that new nestprograms may be added during the production run. In which case therelevant data relating to the cut pieces of the newly added nestprograms are correlated with the previously “denested” data forevaluating the optimal sorting addresses for which the cut pieces fromthe new nest programs are to be routed. This ordinarily is of no probleminsofar as different cut pieces with different dimensions most likelyhad been determined from the nest programs input to the system prior tothe production run. Thus, the same dimensioned cut pieces from the nestprograms can be assigned to the same sorting address, as the productionrun proceeds, so long as there remains available space at thepredetermined location of the unloader. In other words, so long as thestack of cut pieces of a given dimension has not reached a predeterminedheight, cut pieces of the same dimension from the new nest programs canbe routed by the system to the same sorting address. However, in theinstance where the to be cut pieces from the new nest programs have adimension that does not match any of the dimensions previously definedby the nest programs input prior to the production run, the system willcreate new sorting addresses for the newly dimensioned to be cut pieces.These new sorting addresses may be assigned to the same cassette that isin operation, provided that sufficient unused space is available on thatcassette. If not, the system would allocate the new sorting addresses toa new cassette, or other storage devices, such that the sorting andunloading of the newly dimensioned to be cut pieces from the newly addednest programs are smoothly integrated into the same production run.

Inasmuch as the present invention is subject to many variations,modifications or changes in detail, it is intended that all matterthroughout this specification and shown in the accompanying drawings beinterpreted only as illustrative and not in a limiting sense.Accordingly, it is intended that the invention be limited only by thespirit and scope of the appended claims.

What is claimed is:
 1. In a sheet fabricating environment in whichworksheets are cut into finished pieces with each worksheet being cut inaccordance with at least one program routine, a method of unloading saidfinished pieces comprising the steps of: identifying for each productionrun the program routines in accordance with whose programmed operationspieces of different dimensions are to be cut from said worksheets;retrieving from each of said program routines data relating to said tobe cut pieces; utilizing said data retrieved from said program routinesto compute optimal locations at at least one unloading means wherefinished pieces of the same dimension cut in accordance with differentones of said program routines are to be moved to so as to prevent anyconflict in unloading of finished pieces during production run; whereinsaid unloading means comprises a conveyor having a plurality of tiltablesections and at least one receiver means having a storage area, saidmethod further comprising the step of: positioning said receiver meansunderneath said sections of said conveyor; wherein said utilizing stepfurther comprises the steps of: assigning a sorting address to each ofsaid sections of said conveyor; designating by appropriate sortingaddresses which of said sections finished pieces of a given dimensionare to be moved to; moving finished pieces of different given dimensionsto their appropriate sorting addresses; selectively tipping saidrespective sections to enable each finished piece of a given dimensionto be deposited onto a corresponding location at said storage area ofsaid receiver means.
 2. In a sheet fabricating environment in whichworksheets are cut into finished pieces with each worksheet being cut inaccordance with at least one program routine, a method of unloading saidfinished pieces comprising the steps of: identifying for each productionrun the program routines in accordance with whose programmed operationspieces of different dimensions are to be cut from said worksheets;retrieving from each of said program routines data relating to said tobe cut pieces; utilizing said data retrieved from said program routinesto compute optimal locations at at least one unloading means wherefinished pieces of the same dimension cut in accordance with differentones of said program routines are to be moved to so as to prevent anyconflict in unloading of finished pieces during production run; whereinsaid unloading means comprises a stacker mechanism having a plurality ofcoplanar sections each with removable base supports and a receiver meanshaving a storage area, wherein said utilizing step further comprises thesteps of: assigning a sorting address to each of said sections;designating each said sorting address to a specific one of said sectionsto which finished pieces of a given dimension are to be moved; removingthe base supports of respective ones of said sections to whichcorresponding finished pieces of different given dimensions are moved tounload each of said finished pieces of a given dimension from the samesorting address; positioning a predetermined location of said storagearea of said receiver means below said section of said stacker mechanismcorresponding to said same sorting address so that said each finishedpiece of a given dimension is deposited on said predetermined location;whereby finished pieces of respective dimensions are separatelydeposited on corresponding predetermined locations of said storage areaof said receiver means to effect stacks of finished pieces having thesame respective dimensions.
 3. Method of claim 2, further comprising thestep of; routing finished pieces of a given dimension to a differentpredetermined sorting address when the stack of finished pieces of saidgiven dimension at said location of said receiver means reaches apredetermined height; removing the base support of the sectiondesignated with said different predetermined sorting address to unloadfinished pieces of said given dimension onto a different location atsaid receiver means.
 4. Method of claim 2, further comprising the stepof: varying the size of at least one of said sections to enable said onesection to accept finished pieces of various dimensions.
 5. Method ofclaim 2, further comprising the step of: replacing said receiver meanswith another receiver means when the storage area of said receiver meansis determined to be optimally full of finished pieces.
 6. In a sheetfabricating environment in which worksheets are cut by tool means intofinished pieces, a system for unloading said finished pieces comprising:means for inputting program routines to direct said tool means to effectfinished pieces from each of said worksheets; at least one means forunloading said finished pieces; means for identifying said programroutines in accordance with whose programmed operations pieces ofdifferent dimensions are to be cut from said worksheets; means forretrieving from each of said program routines data relating to said tobe cut pieces; means for utilizing said data retrieved from said programroutines to compute optimal locations at said unloading means wherefinished pieces of the same dimension cut from different ones of saidprogram routines are to be moved to so as to prevent any conflict inunloading of finished pieces during production run; wherein saidunloading means comprises: a conveyor having a plurality of tiltablesections; at least one receiver means having a receiving area, saidsections being substantially superposed over said receiving area;wherein each of said sections of said conveyor is assigned a sortingaddress so that finished pieces of different given dimensions are movedto corresponding ones of said sections; and wherein selective ones ofsaid sections are respectively tipped to enable each finished piece of agiven dimension to be deposited onto a corresponding location on saidreceiving area of said receiver means.
 7. In a sheet fabricatingenvironment in which worksheets are cut by tool means into finishedpieces, a system for unloading said finished pieces comprising: meansfor inputting program routines to direct said tool means to effectfinished pieces from each of said worksheets; at least one means forunloading said finished pieces; means for identifying said programroutines in accordance with whose programmed operations pieces ofdifferent dimensions are to be cut from said worksheets; means forretrieving from each of said program routines data relating to said tobe cut pieces; means for utilizing said data retrieved from said programroutines to compute optimal locations at said unloading means wherefinished pieces of the same dimension cut from different ones of saidprogram routines are to be moved to so as to prevent any conflict inunloading of finished pieces during production run; wherein saidunloading means comprises: a stacker mechanism having a plurality ofcoplanar sections each with removable base supports, a sorting addressbeing assigned to each of said sections so that finished pieces havingthe same given dimension are directed to a particular one of saidsections and removable therefrom by the removal of the correspondingbase supports; a receiver means having a receiving area divided intorespective locations each positionable to be below any of said sectionsdesignated by any sorting address so that a predetermined location ofsaid receiver means is positionable below a corresponding sortingaddressed section such that only finished pieces of the same dimensionare deposited thereon; wherein the base supports of respective ones ofsaid sections to which finished pieces of the same given dimension aremoved are removed to deposit finished pieces of the same given dimensiononto the same location of said receiving area.
 8. System of claim 7,wherein said data includes the thicknesses of pieces to be cut inaccordance with said programmed operations; wherein said thicknesses areused by said utilizing means to command said stacker mechanism to routefinished pieces of a given dimension from a first sorting address to analternate sorting address when the stack of finished pieces of saidgiven dimension deposited onto said receiving area of said receivermeans at a first location corresponding to said first sorting addressreaches a predetermined height; wherein the base supports of the sectiondesignated by said alternate sorting address are removed to depositfinished pieces of said given dimension onto said receiving area at adifferent location.
 9. System of claim 7, wherein at least one of saidsections of said stacker mechanism has a receiving area whose dimensionis variable so that said one section can be reconfigured to acceptfinished pieces of varied dimensions routed to its corresponding sortingaddress.